I'm wondering - how to make an own soc? I was searching in soc terminal and on official EU site, but i couldn't find it.

It is a simple button in the society terminal. The problem is you are a member of a society already so it will not allow you create one.

and in order to make the soc persistent it needs to get 5 members within the first week of existence.

Actually I am aware of a society that is now 3 months old and has never had 5 members. They still have the star trek logo thingee but they do indeed still exist.

I think that those societies that ever get the 5 members will eventually get cancelled but it probably has to be done on a manual basis by MA. Who knows. Once they get 5 members steady I think that they will stabilize and lose that risk of being deleted. If you want to create a society, you're gonna have to go to the society terminal first and remove yourself from the society manually and then I think you have to wait a short period of time before you can do it. Either that or its only disbanding societies that has a time delay I'm not really sure.

Don't create a society just for fun, you have to wait 7 days before you can shut it down, and get free again.

5 members are needed at exactly 7 days to make the society stick, after that the leader can stay alone by himself...